Affiliation:
1. Center for Advancing Materials Performance from the Nanoscale (CAMP‐Nano) State Key Laboratory for Mechanical Behavior of Materials Xi'an Jiaotong University Xi'an Shaanxi 710049 China
2. School of Chemical Engineering and Technology Xi'an Jiaotong University Xi'an Shaanxi 710049 China
3. Energy Storage and Distributed Resources Division Lawrence Berkeley National Laboratory Berkeley CA 94720 USA
4. Scientific Research Division National Synchrotron Radiation Research Center Hsinchu Taiwan 30076 ROC
Abstract
AbstractThe application of solid‐state electrolytes in Li batteries is hampered by the occurrence of Li‐dendrite‐caused short circuits. To avoid cell failure, the electrolytes can only be stressed with rather low current densities, severely restricting their performance. As grain size and pore distributions significantly affect dendrite growth in ceramic electrolytes such as Li7La3Zr2O12 and its variants; here, a “detour and buffer” strategy to bring the superiority of both coarse and fine grains into play, is proposed. To validate the mechanism, a coarse/fine bimodal grain microstructure is obtained by seeding unpulverized large particles in the green body. The rearrangement of coarse grains and fine pores is fine‐tuned by changing the ratio of pulverized and unpulverized powders. The optimized bimodal microstructure, obtained when the two powders are equally mixed, allows, without extra interface decoration, cycling for over 2000 h as the current density is increased from 1.0 mA·cm−2, and gradually, up to 2.0 mA·cm−2. The “detour and buffer” effects are confirmed from postmortem analysis. The complex grain boundaries formed by fine grains discourage the direct infiltration of Li. Simultaneously, the coarse grains further increase the tortuosity of the Li path. This study sheds light on the microstructure optimization for the polycrystalline solid‐state electrolytes.
Funder
National Key Research and Development Program of China
National Natural Science Foundation of China
Higher Education Discipline Innovation Project
Office of Energy Efficiency and Renewable Energy
Subject
Mechanical Engineering,Mechanics of Materials,General Materials Science